The present invention relates to an apparatus for assessing the stiffness of a sheet and more particularly, but not exclusively, to an apparatus for assessing the stiffness or crispness of paper sheets such as currency notes.
Prior to the loading of currency notes into currency cassettes for use with ATMs it is important to screen the currency notes to detect their condition. In particular there is a requirement to detect and reject currency notes having holes, voids, soiling or having attachments such as tape or staples. It is also important to detect whether or not a currency note has the necessary degree of stiffness or crispness for satisfactory handling by a cash dispensing mechanism, and, if it does not, the currency note should be rejected to insure that it is not loaded into a currency cassette.
An apparatus for determining the condition of currency notes by assessing their stiffness is disclosed in European Patent Application No. 0073133. This prior art apparatus determines the condition of a currency note on the basis of the noise made by the currency note as it is bent around a bobbin-shaped drum. This prior art technique has the disadvantage that, as a result of noise interference, incorrect determinations of the stiffness of currency notes may be made. A further disadvantage of the prior art apparatus is that the deformation and crinkling of the currency notes as they are passed round the bobbin-shaped drum tend to produce wear of the currency notes, which is contrary to the normal objective of preserving serviceable currency.